According to the Central Dogma, information from DNA flows to protein through RNA. The decoded gene product determines the phenotype of an organism. The gene expression is regulated mainly at transcriptional and translational level. Double stranded RNA molecules are capable of activating a set of RNase III endonucleases influencing gene expression by down regulating corresponding genes through RNA interference (RNAi) pathway. Double stranded RNAs that can induce RNAi pathway falls mainly under 2 categories: miRNAs (endogenous) and siRNAs (exogenous like virus or endogenous retrotransposons). miRNAs are small approximately 22 nucleotide long molecules that carries out transcriptional and post transcriptional regulation of gene expression. miRNA have regulatory roles in developmental timing, patterning, embryogenesis, cell differentiation, organogenesis, stem cell and germline proliferation, growth control, apoptosis, endocrine function fat metabolism in flies (Long et al., 2007; Brennecke et al., 2003; Xu et al., 2003), neuronal patterning, modulation of haematopoetic lineage differentiation in mammals (Chen et al.,2004), control of leaf and flower differentiation in plants ( Aukerman and Sakai, 2003).
No. of Downloads :